$($a$)(2$ points$)$ Assume that after the data has been written to drives $A,B$ and $C$ as explained above, drive $A$ is destroyed. Only drives $B$ and $C$ are left. Explain how each bit a$,$ can be reconstructed from the knowledge of $b_k$ and $c_k.$ Your explanation must be specific and detailed. It is insufficient to declare that $"$ A can be reconstructed from $B$ and $C^{\text{'}\text{'}}$ or such